1. Field of the Invention
This invention relates to a door lock assembly, more particularly to a door lock assembly that has an improved anti-picking effect and that can be manipulated conveniently.
2. Description of the Related Art
It is known that a conventional tubular lock incorporates a spring-biased latch bolt that has a head portion with a tapered face and a flat face. The head portion extends out from a faceplate mounted on a door, and is inserted into a socket portion of a strike plate that is embedded in a doorframe when the door is closed. A handle of the tubular lock can be locked by depressing a push-button into an inside tube of the tubular lock to prevent the door from being opened by an unauthorized person. However, the unauthorized person can easily open the door by extending a stick or the like into the socket portion of the strike plate through a clearance between the door and the doorframe and by pushing the tapered face of the head portion into the door through the opening in the faceplate. Therefore, the anti-picking effect of the tubular lock is relatively poor. Although a conventional mortise can provide an improved anti-picking effect with the use of a dead bolt, the dead bolt must be manipulated by a key when it is desired to lock or unlock the door. This inconveniences the user.
The object of the present invention is to provide a door lock assembly that has an improved anti-picking effect and that can be manipulated conveniently.
According to the present invention, a door lock assembly comprises:
a latching mechanism adapted to latch a door, the latching mechanism including:
an elongated hollow housing which has an outer end, and an inner end opposite to the outer end;
a latch bolt mounted slidably inside the hollow housing adjacent to the outer end of the hollow housing, and including an outer tapered head portion and an inner body portion formed inwardly of the tapered head portion;
an actuating block for actuating the latch bolt, the actuating block having two opposed ends journalled in the hollow housing adjacent to the inner end;
a connecting member disposed inwardly of the latch bolt and connected telescopically to the inner body portion;
a crank arm having opposite first and second ends, the first end being connected to the actuating block so as to be turned by the actuating block to move the second end, the second end being connected to the connecting member so as to move the latch bolt via the connecting member, to a first latching position in which both of the tapered head portion and the inner body portion extend outwardly of the outer end of the hollow housing and a second latching position in which only the tapered head portion extends outwardly of the outer end of the hollow housing, the latch bolt being in the second latching position when the second end is turned to an inward position adjacent to the inner end of the hollow housing, the latch bolt being in the first latching position when the second end is turned to an outward position;
a spring mounted inside the hollow housing for biasing the latch bolt to move to the first latching position;
retaining means disposed on the hollow housing for retaining the second end in the inward position so as to place the latch bolt in the second latching position against the action of the spring;
telescopic joint means for joining the connecting member to the inner body portion so that the latch bolt is retractable inward relative to the connecting member against the action of the spring to move to an unlatching position; and
releasing means disposed inside the hollow housing for causing the second end to be released from the retaining means when the latch bolt is moved to the unlatching position from the second latching position, thereby moving the latch bolt to the first latching position.